Syphon Filtration System

ABSTRACT

A syphon filtration system is a low head, small foot print, long operating cycle, gravity filtration system for treatment of water and wastewater. 
     The filtration system is an apparatus and process with one-stage or two-stage filtration process in one vessel. The filtration system can use different filtration media of sand, anthracite and activated carbon or other proprietary filtration media. 
     The one-stage filtration system is applicable to removal of suspended solids or dissolved impurities. 
     The two-stage filtration system can provide a combination of two different filtration processes for removal of suspended solids and dissolved impurities. 
     The one-stage filtration system has low head room requirements, and the two-stage filtration system has small foot print requirements. 
     In the two-stage filtration system, each filtration stage can be backwashed independently or both stages can be backwashed simultaneously. 
     The filtration system uses novel syphon piping and controls design which extend the filtration operating cycle and reduce the filter apparatus headroom, and the filter backwash water volume requirements.

FIELD OF THE INVENTION

The invention is an apparatus and process for treatment of water andwastewater for removal of suspended solids and dissolved impurities.

BACKGROUND OF THE INVENTION

Filtration systems are used for treatment of water and wastewater forremoval of suspended solids and dissolved impurities.

The filtration systems are usually one-stage, gravity or pressure flowsystems.

The gravity flow filtration systems depend on a static water pressure(head) above the filter media for the water to flow through the media.The available static water pressure above the filter media is directlyproportional to the filtration operating cycle before the filter mediahas to be backwashed. Therefore, the higher the filter vessel above thefilter media the longer the operating cycle is expected for the samewater quality and flow rate treated.

The filtration systems are usually provided for removal of suspendedsolids or dissolved impurities and each usually requires an independentfiltration apparatus.

If two stage suspended solids filtration system is required, twoindependent filtration apparatus', operating in series are used

Similarly, if suspended solids filtration and dissolved impuritiesfiltration processes are required two independent filtration apparatus,operating in series are used.

Filter media need to be backwashed and rinsed after they are pluggedwith the impurities which they remove. Each filtration apparatus isbackwashed and rinsed independently. The backwash and rinse water ispredominantly wasted.

The invention offers several advantages over the conventional filtrationsystems as follows:

-   -   The novel syphon piping and control system, used in this        invention, allows for reduction of the filter headroom        requirements and it extends the filter operating cycle between        the filter backwashings.    -   The novel syphon piping and control system design prevents the        filter media from being exposed and washed out on the surface        during the filtration process.    -   The novel syphon piping and control system design uses simple        open/close automatic valves to control the water level above the        filter media and to perform the backwashing and rinsing        processes.    -   The two-stage filtration system in one apparatus reduces the        foot print requirements.    -   The two-stage filtration system permits simultaneous backwashing        and rinsing of the filter media in both stages of the filtration        system which reduces the backwash water requirements.    -   The two-stage filtration system in one apparatus requires less        extensive controls and reduces the costs of the treatment        system.

BRIEF SUMMARY OF THE INVENTION

The filtration system of the present invention is a process andapparatus for treatment of water and wastewater for removal of suspendedsolids and dissolved impurities.

The filtration system as shown on FIG. 1 uses a novel siphon piping andcontrol system design which results in a lower head room requirements,an extended filtration cycle, a less frequent backwashing, a lowerbackwash wastewater volume and a lower filtration down time.

The two-stage filtration system in one apparatus, as shown on FIG. 2,results in a smaller footprint requirement and it lends itself toperforming two different filtration processes such as a roughing andpolishing filtration for removal of suspended solids, and a filtrationprocess for removal of suspended solids and an adsorption filtration forremoval of dissolved impurities in one apparatus.

The two-stage filtration system uses the one-stage syphon piping andcontrol system design.

The two-stage filtration system backwashing of the filtration media canbe done separately for each stage or jointly for both stages whichresults in a reduction of the backwash water volume requirements.

The filtration system comprises:

-   -   A vessel of steel, plastic, concrete or wood construction,        vertical and preferably round, square or rectangular in cross        section, approximately two to four meters in height.    -   Filtration media of sand, anthracite, activated carbon or other        proprietary adsorption or non-adsorption type media.    -   Piping and control valves with a syphon arrangement.    -   A water level sensor and controller for activation of the syphon        piping and the first-stage filtration media backwashing.    -   A deferential pressure control gauge for activation of the        second stage filtration media backwashing.    -   A main controller for control of the operation of the control        valves and the first and the second stage filter backwashing        processes.

Both, the one-stage and two-stage filtration systems operation can befully automated with a PLC control system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Having thus generally described the invention, it will be referred tomore specifically by reference to accompanying drawings illustratingpreferred embodiments, and in which:

FIG. 1 is a diagrammatic illustration in vertical cross-section of theone-stage syphon filtration system.

FIG. 2 is a diagrammatic illustration in vertical cross-section of thetwo-stage syphon filtration system.

DETAILED DESCRIPTION OF THE INVENTION

According of the embodiment of the invention, as shown on FIG. 1, thesyphon filtration system comprises; a filter unit 1, filter piping andcontrol valves 28, a filter controller 41.

The filter unit 1 comprises; a filter vessel 2, filter media 3, a filterunderdrain system 4, an outlet water internal pipe 5, a water levelsensor and controller 6, an inlet water external pipe 12, an inlet waterexternal valve 13, an inlet water internal distribution pipe 14, and abackwash water collector trough 15.

The filter piping and control valves 28 comprise; an outlet water pipe16, an outlet water control valve 17, an outlet water syphon pipe 18, anoutlet water discharge pipe 19, a syphon control valve 20, a syphon ventpipe 21, a rinse water discharge pipe 22, a rinse water control valve23, a backwash water supply pipe 25, a backwash water control valve 26,a backwash water rate of flow control valve 27, a backwash waterdischarge pipe 29, and an air vacuum pump 30.

The filter controller 41 comprises indicating lights, switches, relays,and a PLC, and it is connected to the water level sensor and controller6 and the control valves 17, 20, 23, and 26, with control wires 42.

The water level sensor and controller 6 provides inputs to the filtercontroller 41 on water levels 8 and 9 in the filter vessel 2.

The filter controller 41 controls open and closed status of the controlvalves 17, 20, 23 & 26 according to the water levels 8 & 9 in the filtervessel and a time logic program contained in the PLC.

The filter media 3 can be a single or multi-media composed of sand,anthracite, activated carbon or other proprietary media designed toremove specific suspended solids or dissolved impurities.

The filter underdrain system 4 can be made of sand and gravel, single ormultilayer or constructed with a false bottom with slotted or perforatednozzles provided with metering tubes for air scour before the waterbackwashing.

The inlet water external pipe 12 is provided with an inlet water valve13 which is a non-return valve in a gravity inlet water supply system.

The backwash water collector trough 15 is a slotted or perforated pipeto collect the backwash water from the entire cross-section of thefilter vessel 2.

The outlet water syphon pipe 18 is located above the filter media 3,preferably 150 to 200 mm, to ensure a minimum water level 7 of 150 to200 mm in the filter above the filter media 3.

The inlet water enters the filter through the inlet water external pipe12, the non-return valve 13 and the internal distribution pipe 14, andit flows downward as indicated by an arrow 10. The inlet water passesthrough the filter media 3, the underdrain system 4, the outlet internalpipe 5, the external outlet pipe 16, the control valve 17, the syphonpipe 18 and the discharge pipe 19.

The backwash water is provided through the backwash water supply pipe25, the control valve 26 and the rate of flow control valve 27 into thepipe 5, and the underdrain system 4, the filter media 3, and it flowsupward, as indicated by an arrow 11, into the backwash water collectortrough 15 and the discharge pipe 29.

During the rinse cycle, the inlet water flows through the filter media 3into the underdrain system 4 and the outlet pipes 5 and 16 and the rinsewater discharge pipe 22 to the backwash water discharge pipe 29.

The filter operating cycles comprise a filtration cycle without syphonaction, a filtration cycle with syphon action, a backwashing cycle and arinsing cycle.

During the filter operating cycles the control valve status is asfollows:

-   -   Filtration cycle without syphon action:        -   The control valve 17 is open.        -   The control valve 20 is open.        -   The control valve 23 is closed.        -   The control valve 26 is closed.    -   Filtration cycle with syphon action:        -   The control valve 17 is open.        -   The control valve 20 is closed.        -   The control valve 23 is closed.        -   The control valve 26 is closed.    -   Backwashing cycle:        -   The control valve 17 is closed.        -   The control valve 20 is closed.        -   The control valve 23 is closed.        -   The control valve 26 is open.    -   Rinsing cycle:        -   The control valve 17 is closed.        -   The control valve 20 is open.        -   The control valve 23 is open.        -   The control valve 26 is closed.

The filtration with the syphon action is provided by the filterdischarge pipes 16, 18 & 19 arrangement in an inverted ‘U’ shape andclosure of the control valve 20. By opening of the control valve 20 thesyphon action is lost and the filter operates without the syphon action.

The syphon action is activated by closing the control valve 20 when thewater in the filter vessel 2 reaches the level 8. This operation iscontrolled by the water level sensor and controller 6 and the filtercontroller 41.

The syphon action causes the water level in the filter vessel 2 to dropinitially, but the water level will rise again, after a certain time, asthe filter media 3 are further plugged with the water impuritiesretained by the filter media.

When the water level in the filter vessel 2 reaches the level 9 thebackwashing cycle is activated and it continues for a predeterminedperiod of time, controlled by the filter controller 41.

The filter rinsing cycle follows immediately the backwashing cycle for apredetermined period of time, controlled by the filter controller 41.

After the rinsing cycle, the filter operation returns to the filtrationcycle without the syphon action.

During the filtration cycle with the syphon action air or other gas maybe released from the water and it may accumulate in the filter syphonpipe 18. If this condition is detected the air vacuum pump 30 isactivated to remove the air or other gas from the syphon pipe 18. Thisensures an efficient action of the syphon piping system.

The rinse water discharge pipe 22 is connected to the backwash waterdischarge pipe 29 at the same level as the syphon pipe 18 elevation, toensure that the water level in the filter vessel 2 does not drop belowthe low water level 7 during the filter rinsing cycle. This prevents thefilter media 3 from being exposed and disturbed on the surface by theinlet water.

A second embodiment of the invention is shown on FIG. 2.

For the various embodiments disclosed here, the same reference numeralnumbers are used for the same or substantially similar features.

The filter vessel 2 comprises two independent filter media 3 and 31, twoindependent underdrain systems 4 and 32, two independent water outletpipes 5 and 33, two independent backwash water collecting troughs 15 and34, and two independent backwash water supply pipes 25 & 38 and controlvalves 26 & 39 and rate of flow control valves 27 & 40.

The other additional features comprised in this embodiment are controlvalves 35, 36 & 37, and a differential pressure switch 43.

The filter operating cycles are the same in this embodiment as thoseoutlined in the first embodiment and they comprise:

-   -   Filtration without the syphon action.    -   Filtration with the syphon action.    -   Backwashing.    -   Rinsing.

The filter backwashing can be performed jointly or independently forboth filter media 3 and 31 followed by a joint or independent rinsingcycles of each filter media respectively.

If a joint filter backwashing and rinsing cycles are performed for bothfilter media 3 and 31, the filter media 3 backwashing and rinsing cyclescan be extended beyond those performed for the filter media 31 asrequired.

The various combinations of the backwashing and rinsing cycles areoutlined as follows:

-   -   Joint backwashing of both filter media 3 and 31:        -   The control valves 35 & 39 are open, the backwash water            supply is provided from pipe 38.        -   The control valves 17, 20, 23, 36, 37 & 26 are closed.        -   The backwash water flows upward through the filter media 31            and 3 to the backwash water collecting trough 15 and            discharge pipe 29.    -   Joint rinsing of both filter media 3 & 31:        -   The control valves 20, 23 & 35 are open.        -   The control valves 17, 26, 36, 37 & 39 are closed.        -   The rinse water flows downward through the filter media 3            and 31 to the discharge pipe 33 and the rinse water            discharge pipe 22 and the backwash water discharge pipe 29.    -   Independent backwash and rinsing cycles of the filter media 3:        -   Backwashing Cycle        -   The control valve 26 is open.        -   The control valves 17, 20, 23, 35, 36, 37 & 39 are closed.        -   The backwash water supply is provided from the pipe 25 and            the water flows upward through the filter media 3 to the            backwash water collecting trough 15 and the backwash water            discharge pipe 29.        -   Rinsing Cycle        -   The control valves 37, 23 & 20 are open.        -   The control valves 17, 35, 36, 37 & 39 are closed.    -   Independent backwashing and rinsing cycles of the filter media        31:        -   Backwashing Cycle        -   The control valves 39 & 36 are open.        -   The control valves 17, 20, 23, 26, 35 & 37 are closed.        -   Rinsing Cycle        -   The control valves 23, 35 & 20 are open.        -   The control valves 17, 36, 37, 39 & 26 are closed.

1. A syphon filtration system comprises: A filter vessel. Filtrationmedia. Piping and control valves. Water level or pressure sensors andcontrollers. A main controller.
 2. A syphon filtration system of claim 1wherein said filter vessel is vertical, open or closed, vented top,non-pressure vessel.
 3. A syphon filtration system of claim 1 whereinsaid filtration media can be one or two-stage, single or multi-layergranular media, made of sand, anthracite, activated carbon or otherproprietary granular media.
 4. A syphon filtration system of claim 3wherein said two-stage filtration media are located in a single vesselof claim 2 divided into upper and lower compartments.
 5. A syphonfiltration system of claim 4 wherein said two-stage filtration media canbe designed to perform removal of suspended solids in both stages orremoval of suspended solids in the first stage and removal of dissolvedimpurities in the second stage, or removal of dissolved impurities inboth stages, operating in series.
 6. A syphon filtration system of claim1 wherein said piping and control valves are designed to cause a syphonaction in the outlet water flow which induces a vacuum or loweratmospheric pressure in the filter media outlet pipes and which resultsin higher water flow rates through the filter media.
 7. A syphonfiltration system of claim 6 wherein said piping and control valvessyphon action is developed by an inverted ‘U’ shape discharge waterpiping design with a control valve which controls the piping ventingcondition and the syphon action.
 8. A syphon filtration system of claim7 wherein said inverted ‘U’ shape discharge water piping is positionedsuch that the upper part of the inverted ‘U’ shape piping is locatedabove the first stage filtration media in order to prevent the waterlevel in the first stage filtration to drop to or below the top of thefirst stage filtration media.
 9. A syphon filtration system of claim 7wherein said piping and control valves syphon action is enhanced by avacuum pump which helps to remove air or other gas from the inverted ‘U’shape discharge water piping.
 10. A syphon filtration system of claim 1wherein said piping and control valves are designed to allow the filteroperation in several different cycles; filtration without syphon action,filtration with syphon action, filter media backwashing and filter mediarinsing.
 11. A syphon filtration system of claim 10 wherein said filtermedia backwashing and rinsing can be performed in two different ways inthe two-stage filtration system and which includes simultaneousbackwashing and rinsing of the filter media in both stages, andindependent backwashing and rinsing of the filter media in each stage.12. A syphon filtration system of claim 1 wherein said piping andcontrol valves include inlet water piping and control valves, outletwater piping and control valves, filter media backwashing piping andcontrol valves and the filter media rinsing piping and control valves.13. A syphon filtration system of claim 12 wherein said filter mediabackwashing piping comprises backwash water collecting trough andbackwash water discharge piping.
 14. A syphon filtration system of claim12 wherein said filter media rinsing piping is connected to the filtermedia backwashing discharge piping at the same or near the level of theinverted ‘U’ shape filter discharge water upper pipe in order to preventthe water level in the first stage filtration to drop to or below thetop of the first stage filtration media.
 15. A syphon filtration systemof claim 12 wherein said inlet water piping is provided with anon-return valve and an inlet water internal distribution pipe locatedbelow the backwash water collecting trough.
 16. A syphon filtrationsystem of claim 13 wherein said filter media backwashing collectingtrough is located near the top of the said filter vessel of claim 2 inorder to allow for a maximum expansion of the first stage filter mediaduring the backwashing cycle and to provide maximum available headduring the filtration cycle.
 17. A syphon filtration system of claim 13wherein said filter media backwashing collecting trough is located nearthe top of the lower compartment of said filter vessel of claim 4 inorder to allow for a maximum expansion of the second stage filtrationmedia during the backwashing cycle.